This invention relates to an in-ground tank measuring system for monitoring the level of gasoline and other fuels and more particularly to an arrangement which safely, economically, and conveniently gives instantaneous and accurate readings of fuel levels in underground tanks such as those employed in gasoline stations.
In many if not most automobile service stations which dispense gasoline and other liquid fuels, underground tanks store the fuels and dip sticks are employed to take readings of the levels within the tanks at frequent intervals. Hence the process of keeping track of the amounts dispensed is very rough and cannot be relied upon for accurate information.
The use of dip sticks for this purpose at this time as the preferred technique for keeping track of the amount of fuel still in storage is probably due at least in part to the great expense and complexity of automatic measuring systems which have been devised up to now, and possibly due in part to certain risk factors involved especially in the case of gasoline which is highly volatile.
Some of these automatic level monitoring systems are shown in U.S. Pat. Nos. 3,074,274, 3,459,042, 3,935,741, 3,972,235, and 4,255,859. In the patent to Frazer, it is noted that an electrical current passes through conductors within the tank, and this arrangement is considered too dangerous for normal use. Only the patents to Frazer and Klieman appear to show the monitoring of more than one tank at a time, and all arrangements are too complex and expensive for use by a local gasoline station.